Abstract: A process is disclosed for preparing a polyacrylate-modified polyvinyl chloride processing aid for polyvinyl chloride by sequentially polymerizing the vinyl chloride and the desired acrylate ester monomer. Thus, a conventional vinyl chloride suspension polymerization is conducted at a controlled rate of agitation and in the presence of a specified concentration of suspending agent and is then halted at or near its completion; unreacted vinyl chloride monomer is removed, a minor proportion of an acrylate ester monomer, e.g., methyl methacrylate, which has been pre-mixed with a fresh supply of a free radical initiating catalyst is added and polymerization is resumed and continued until the acrylate ester monomer polymerizes in and/or on the particles of the previously polymerized polyvinyl chloride. The polyacrylate-modified PVC thereby recovered is an effective aid for processing conventional PVC, or it can be processed per se since it is suitable for calendering or extruding.